The present invention relates to an ink jet recording head and an ink jet recording apparatus capable of forming an image by discharging ink onto a recording medium, and is intended to ensure that when a protective member is peeled off from a recording head when the header is mounted on the recording apparatus, adhesive material is not deposited in the vicinity or periphery of the ink discharge port, since ink discharge failure can result from such adhesive material remaining in that vicinity.
Recording utilizing an ink jet system recording head is widely employed as an image recording apparatus for information communication equipment such as printers, plotters, copying apparatus, word processors, facsimile apparatus, etc. Among such ink jet systems, the so-called bubble jet system utilizing the pressure of a bubble generated by an electrothermal converting member (as disclosed in Japanese Patent Applications Laid-Open Nos. 61-59911 to 61-59914) has the advantages of easily achieving compactization of the apparatus and a high image density in the images produced using such a system.
Such a recording head has the possibility of causing unstable ink discharge, resulting in the deterioration of print quality, due to:
1) adhesion of dust or the like in the ink discharge port of the recording head in the course of delivery (shipment) from the factory to the user through the transportation and warehouse storage;
2) evaporation of a part of the components of the ink in the vicinity of the discharge port, resulting in an increase in ink viscosity;
3) leakage of ink from the discharge port due to vibration, or being dropped, during transport; and
4) deformation of the discharge port due to mechanical shock in the course of transport.
In order to prevent such phenomena and to ensure the reliability of the printing operation, there has been adopted a method of applying a protective member in the vicinity of the discharge port and on the surrounding members, and further providing a cap member.
However, at the mounting of the recording head on the recording apparatus by the user, in order that the user does not forget to peel off the protective member, and in order that the protective member has a sufficient length to facilitate peeling by the user, there has been adopted a method of covering a peripheral area considerably larger than the necessary portion with a protective member in order to shield the discharge port from the exterior.
Such protective member is generally composed of a film substrate coated with an adhesive material, but, in consideration of the cost and efficient production of the protective member, there is employed an protective member bearing adhesive material not only on the necessary portion but on the entire surface to be attached to the recording head.
In such case, the adhesive material of the protective member adheres not only in the vicinity of the discharge port but also on the peripheral members over a considerably wire area, and, if the adhesive material adheres strongly to the recording head, for example, in the course of transportation after shipment from the factory, the adhesive material or a part thereof remains on the recording head at the peeling off of the protective member by the user, with the result that the recording head is mounted on the recording apparatus in a state bearing the adhesive material in the vicinity of or around the discharge port.
As a result, the adhesive material may directly cover the discharge port, and induce failure in the ink discharge, and the adhesive material remaining in the vicinity of the discharge port may be pushed thereinto by the wiping operation of the cleaning blade, resulting in failure in ink discharge or instability in the ink discharging angle, thereby significantly degrading the print quality.
In consideration of the foregoing, the object of the present invention is to avoid, with an extremely simple configuration, defective ink discharge resulting from adhesion of the adhesive material in the vicinity of or around the discharge port when the user peels off the protective member in mounting the recording head on the recording apparatus, thereby securely preventing defective printing inexpensively and providing an ink jet recording head and an ink jet recording apparatus of higher reliability.
The foregoing object can be attained, according to the present invention, by a configuration of the ink jet recording head including a discharge port forming member for forming an ink discharge port, an ink supply member for supplying ink to the discharge port forming member from an ink container, an ink discharge port formed by the discharge port forming member and discharge pressure generating means for generating a discharge pressure for discharging ink from the discharge port, where a discharge port forming face of the discharge port forming member and a face of the ink supply member are substantially coplanarly connected, a protective member is adhered to both faces, and the adhering area of the protective member per unit area of the ink supply member is smaller than that in the discharge port forming face.
In another aspect, in the ink jet recording head of the present invention, the adhering area per unit area is decreased in the vicinity of the ink discharge port by forming an irregularity on the surface of the protective member adhering to a portion of the surface other than the vicinity of the discharge port.
In another aspect of the present invention, the adhering area of the protective member per unit area other than the vicinity of the ink discharge port does not exceed 30%, preferably 10%, of the adhesive area of the protective member per unit area in the vicinity of the ink discharge port.
In still another aspect of the present invention, the adhering area per unit area is decreased in the vicinity of the ink discharge port by forming a fine irregularity on a portion of the surface other than the vicinity of the discharge port, on which the protective member is to be adhered.
In still another aspect of the present invention, the adhering area per unit area is decreased in the vicinity of the ink discharge port by forming plural recesses of a circular shape or a polygonal shape, such as a tetragonal shape, on a portion of the surface other than the vicinity of the discharge port, on which the protective member is to be adhered.
Alternatively, that the smaller adhesive area in the vicinity of the ink discharge port is attained by forming a plurality of grooves parallel to an array of the discharge ports, on a portion of the surface other than the vicinity of the discharge port, on which the protective member is to be adhered, or by forming a plurality of grooves unparallel to an array of the discharge ports, on the surface portion other than the vicinity of the discharge port, on which the protective member is to be adhered.
According to another aspect of the present invention, the protective member, in peeling perpendicularly to the face of the ink supply member and the discharge port forming face in succession in this order, has a vertical peeling adhesive force not exceeding 120 gf, preferably 80 gf, on the surface portion other than the vicinity of the discharge port.
Also, in the ink jet recording head of the present invention, the pressure generating means may be an electrothermal converting member.
In an ink jet recording apparatus of the present invention, the recording head may be arranged to have the features of any of the above-mentioned ink jet recording heads of the present invention.